Another question about the car I'm looking at purchasing is that it has a cowl induction hood (no wiring/not operable w/value, but insulated). The CRG 1968 guide says that no 1968 came from the factory with a cowl induction hood. From this, can it be assumed that the car had the hood added by another prior owner, or was this an available dealer installed option?

The cowl induction hood (RPO ZL2) was not an option for the 1968 model year. It has been installed by a prior owner. Cowl induction for 1967 and 1968 was available as an option for the Z/28 and was an air cleaner assemble that had an air duct bolted up to the fire wall.